Quantitative Susceptibility Mapping Values Quantification in Deep Gray Matter Structures for Relapsing-Remitting...

Area of Science:

• Neuroimaging
• Neurodegeneration
• Multiple Sclerosis Research

Background:

• Deep gray matter (DGM) iron dysregulation is implicated in multiple sclerosis (MS) pathogenesis.
• Quantitative susceptibility mapping (QSM) is a novel MRI technique to assess iron levels.
• Relapsing-remitting MS (RRMS) is the most common form of MS, characterized by distinct neurological episodes.

Purpose of the Study:

• To systematically review and meta-analyze the role of magnetic susceptibility (χ) in DGM structures (putamen, globus pallidus, caudate nucleus, thalamus) in RRMS.
• To utilize QSM to quantify susceptibility differences between RRMS patients and healthy controls (HCs).
• To explore potential biomarkers for neurodegeneration in RRMS.

Main Methods:

• Systematic literature review up to November 2023 following PRISMA guidelines.
• Random-effects model meta-analysis to calculate standardized mean difference (SMD) in QSM values.
• Assessment of publication bias and risk of bias.

Main Results:

• Significantly higher QSM values (indicating increased iron) were observed in the putamen, globus pallidus, and caudate nucleus of RRMS patients compared to HCs.
• No significant QSM differences were found in the thalamus between RRMS patients and HCs.
• Subgroup analyses revealed that younger RRMS patients (<40 years) and those with higher male proportions exhibited more pronounced susceptibility changes in the putamen, globus pallidus, and caudate nucleus. Thalamic QSM decreased in older RRMS patients (>40 years) and those with higher male proportions. Early-stage RRMS showed higher QSM in basal ganglia, while later stages showed lower QSM in the thalamus.

Conclusions:

• QSM can serve as a valuable biomarker for detecting iron dysregulation in DGM structures in RRMS.
• Altered magnetic susceptibility in the basal ganglia nuclei (putamen, globus pallidus, caudate nucleus) is a key feature of RRMS.
• QSM findings highlight the potential role of iron dysregulation and neurodegeneration in the pathophysiology of RRMS.